Histochemical detection of zinc and copper in various neurons of the central nervous system.

Trace elements (Zn2+, Cu2+, Fe2+) were localized with Timm's sulphide silver method in the neurons (pyramidal cells, Purkinje's cells, motoneurons) and in the axon terminals of various regions cortex, hippocampus, nucleus ruber, cerebellum, medulla spinalis) of the central nervous system. After treatment of the same tissues with 15% trichloroacetic acid, a considerable proportion of the coarse granular staining disappeared from certain neurons (Purkinje's cells, ncl. ruber cells, motoneurons) and axon terminals (hippocampus mossy fibres), while in other cells (cortex pyramidal cells) and axon terminals it remained. The results suggest that the decrease in the staining is a consequence of the loss of Zn2+ and Fe2+ from the neuronal perikaryon or axon terminal. The histochemical results are supported by quantitative atomic absorption measurements.